Automatic electric switch.



.No. 884,514. I PATENTED APR. 14, 1908.

-. A. H. MILLER.

AUTOMATIC ELECTRIC SWITCH. APPLICATION FILED m. so, 1903.

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ANDREW H. MILLER, OF GHESANING, MICHIGAN.

AUTOMATIC ELECTRIC SWITCH.

Specification of Letters Patent.

Patented April 14, 1908.

Application filed March 30, 1903. Serial No. 150,213.

' To all whom it may concern:

Be it known that I, ANDREW I-I. MILLER, residing at Chesaning, in the county of Saginaw and State of Michigan, a citizen of the United States, have invented certain new and useful Improvements in Automatic Electric Switches, of which the following is a speci- 'lication, reference being had therein to the accompanying drawings.

The invention relates to automatic electric switches, and is more particularly designed for use for the periodic opening or closing of electric circuits. I The invention consists in the peculiar construction, arrangement and combination of parts. as hereinafter set forth.

In the drawings, Figure 1 is a section through an incandescent lamp bulb to which lily-invention is applied. Fig.2 is a ers ective view of a thermo-dynamic switcli. ig- 3 is an enlarged section on line a a: Fig. 1. Fig. 4 is a section similar to Fig. 1, showing a modification, and, Fig. 5 is a diagram illustrating one application of the invention.

I shall show and describe'my invention as used in connection with incandescent electric lamps, but it is obvious that it is equally well adapted for any other use where the periodic opening and closing of an electric circuit is desired.

As shown, A is an electric lamp bulb-containing the filament B and provided with the usual terminals C and D, the former constituting a screw threaded cap for engaging the lamp socket. The thermo-dynamic switch which as shown in Fig. 1 is arranged within the ca C and consists of a composite bar of metal E or other material adapted to be flexed by the unequal expansion of its constituent arts.

.l preferab ly employ two dissimilar metals such as brass and tin, strips of which are sol dered together to form the composite bar. This bar is preferably of the curved form shown so that it may be conveniently arranged within the lamp socket, and one end is soldered or otherwise secured to the cap C. The opposite end of the bar is preferably provided with a tip a of platinum or other noncorrosive metal, and which is adapted to normally contact with a cooperating contact E. This contact is preferably formed of a strip of metal secured to but insulated from the cap C. Its free end is provided with a ti b correspoiliding to the tip a and contacting there- Wll is diverted theret irough.

To generate the heat for operating this therino-dynainic switch, an electric heater F is employed. This is shown to be formed in the shape of a ring composed of some material of high resistance. A suitable substance for this purpose may be formed of powdered carbon mixed with some cementitious nonconducting material, the proportions being such as to obtain the proper resistance in the composite body.

The ring F is preferably of a size so that its outer edge is in proximity to the bar E leaving sufiicient clearance for the free movement of said bar. The heater F is connected to the terminal of the lamp preferabl in shunt with the filament B, and as it is of 'gh resistance, a small ortion only of the current The current in both the heater and in the filament is controlled by the switch and to this end one terminal c of the heater and one terminal (1 of the filament are connected to the terminal contact D. The op osite terminals e and f of the heater and ainent respectively are connected to the contact E, which contact is normally in engagement hith the contact on the bar E, the latter being connected to the terminal contact C.

In 0 eration when the lamp is secured in its soc 'et the current will pass through the switch and will then be divided, a portion passing through the filament B and another portion through the heater F. The resistance of the latter will cause the generation of heat which is communicated to the composite bar E and after a definite period of time will cause the warping of said bar so that it will break contact with the cooperating member E. To prevent sparking a spring catch H is preferably arranged to temporarily arrest the movement of the contact a until sufficient tension is placed on the bar E to spring out of engagement with said catch. The contact a will then disengage from the cont-act b by a quick movement which will prevent the forming of an arc.

The opening of the contact will break the circuit in both the filament and the heater. This will stop the generation of the heat and after a definite period of time the contraction of the bar will again throw the cont-acts (1 against the contacts I). It is evident from this description-that the circuit will be periodically opened and closed and will thus produce a flashing of the lam Instead of placing the eater and switch within the cap of the lamp bulb they may be placed in the lam socket as illustrated in ig. 4, in which is a heater, E is the switch, the connections being similar to those shown in the other arrangement.

In Fig. 5 is shown a display board having a series of lamps G placed therein, each of which is provided with the thermo-d namic switch of the character described so t at the lam s will be periodically flashed.

hat I claim as my invention is:

1. The combination with an electric lamp and a circuit therefor, of means for periodically flashing said lam comprising an electric heater independent 0 the lamp filament and operated by said circuit, and a thermo-dynamic switch operated by said heater and controlling said circuit.

2. The combination with an electric lamp and a circuit therefor, of means for periodically flashing said lamp, comprising an electric heater independent of the lamp filament and operated by said circuit, a thermo dynamic switch operated by said heater and controlling said circuit, and means for inclosiug and protecting said heater and switch from external influences.

. 3. The combination with an electric lamp and a circuit therefor, of means for periodically flashing said lamp, comprising an electric heater independent of the lamp filament and operated by said circuit, a thermo dynamic switch operated by said heater and controlling said circuit, and means associated with said lamp for protecting said heater and switch from external influences. V

4. An electric lamp having .a filament, va switch comprising cooperating contacts, an actuating device for one of said contacts and comprising a composite bar formed of a plurality of members having unequal co-eflicient of ex ansion, an electric heater adjacent to said ar connected to the terminal of the lamp, means for inclosing said actuating deelectric lamp and the circuit therefor, of an electric heater independent of the filament, a thermo-dynamic switch operated by said heater, means for inclosing said switch and heater, and a catch on said inclosing member for temporarily arresting movement of said switch, whereby it will finally snap open with a quick movement.

7. The combination with an electric lamp,

of an electric heater in shunt therewith, a thermo-dynamic switch, operated by said heater, a protective cap or casing for the heater and switch, and means therewithin for temporarily arresting movement of said switch whereby it will open with a quick movement. I

8. The combination with an electric lamp bulb, a filament within the bulb, an electric circuit therefor, a socket for the bulb having a contact included in said circuit, a switch within the socket for opening and closing the circuit through the filament, and a thermodynamic actuating device for said switch, including a heater within said socket and independent of said filament.

In testimony whereof I aflix my signature in presence of two witnesses.

ANDREW H. MILLER.

Witnesses:

L. W. Evmrs, ERASTUS WIERMAN. 

